A unified quantum theory of mechanics and thermodynamics. Part III. Irreducible quantal dispersions

This part of the paper concludes the presentation of the unified theory. It is shown that the theory requires the existence of, and applies only to, irreducible quantal dispersions associated with pure or mixed states. Two experimental procedures are given for the operational verification of such dispersions. Because the existence of irreducible dispersions associated with mixed states is required by Postulate 4 of the theory, and because Postulate 4 expresses the basic implications of the second law of classical thermodynamics, it is concluded that the second law is a manifestation of phenomena characteristic of irreducible quantal dispersions associated with the elementary constituents of matter.Parts I, IIa, and IIb of this paper appeared inFound. Phys. 6, 15, 127, 439 (1976), respectively. The numbering of the sections, equations, and references in this part continues from the previous parts.